The present invention relates to a method of purifying coral, and to the coral obtained by said method.
The invention is of particular application in the medical field.
Coral, which has a porous structure, is essentially (about 97%) composed of mineral material, mainly calcium carbonate, with the remainder (about 3%) being constituted by oxides of magnesium and iron together with organic substances which are responsible for its color. Its hardness varies from 2.5 to 3.5 on the Mohs scale.
The constituent calcium carbonate of coral has a metastable aragonite type crystallographic structure which can easily be transformed into calcite, especially under the effect of a temperature of about 260° C.
The organic matter in coral contains a proteinaceous material, but it is substantially free of lipid material.
Several bone substitutes based on coral currently exist and have been approved by the Agence Française de Sécurité Sanitaire des Produits de Santé (AFSSAPS) [French Health Safety Products Agency]. One of those products, sold by INOTEB under the trade name BIOCORAL®, is obtained by treating the coral at the surface of its pores, which can eliminate a portion of the organic substances mentioned above.
A more thorough morphological analysis of coral (thermal scanning electron microscope coupled with mass spectroscopy) shows, however, that said organic substances are present not only in the pores of the coral, but also at the grain boundaries of the calcium carbonate particles. The treatment carried out for the BIOCORAL® product cannot extract organic substances located at the grain boundaries, which represents about 90% of the total organic substances.